In the injection molding apparatus equipped with a clamping and an injection units disposed confronting each other, injection is performed by causing the tip of the nozzle of the injection unit to abut against the dies fixed to the clamping unit. When the dies have been changed, the cylinder assembly of the injection unit has been changed, or when the injection unit has been turned for change of the parts, it is necessary to check, at the time of the nozzle touching operation, whether the tip of the nozzle of the injection unit accurately abuts against the sprue bush of the dies while operating the injection unit manually or at a low speed.
For this purpose, the abutment between the sprue bush and the injection nozzle tip, i.e. the condition of nozzle touch, is conventionally monitored through a clearance formed in the vicinity of the purge shield by an operator looking into the front side of the stationary platen (a surface on the side of the injection unit) from the front side of the clamping unit. However, a point where the sprue bush and the injection nozzle tip abut each other tends to locate in a dark place far inward from the front side of the stationary platen. Thus, it has been difficult for the operator to accurately monitor the condition of abutment.
This difficulty increases as the size of the injection molding apparatus increases, since the size of the stationary platen also increases accordingly. Thus, there has been a possibility of having the resin leaked outside due to improper nozzle touch.